There have been used in the past various jack bolt devices for effecting the tightening of a nut of the head of a bolt against a support. In such devices the extreme pressure that may be exerted has provided a problem in the wear, friction and equalization of pressure to be exerted. In view of the extreme pressure that may be exerted and the desirability to provide ease in the application of the pressure and equalization of force to prevent distortion there has remained a need to provide a device to satisfy such requirements.
There have also been provided in the past various devices for sensing the stress placed upon the elongated shanks of bolts or studs employed to fasten together elements used in industry and construction. When such devices are used the stress placed upon the shank must be accurately sensed to determine the proper force used in tightening the elements to prevent accidental loosening with attendant danger to equipment and personnel should the elements be separated. Such devices should be capable of ease in tightening with ready accessability and proper pressure application to provide equalized stress distribution.